/*
 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.tools.javac.code;

import static com.sun.tools.javac.code.Flags.DEPRECATED;

import java.util.EnumSet;
import java.util.HashMap;
import java.util.Map;

import com.sun.tools.javac.code.Symbol.MethodSymbol;
import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.Options;
import com.sun.tools.javac.util.Pair;

/**
 * A class for handling -Xlint suboptions and @SuppresssWarnings.
 * 
 * <p>
 * <b>This is NOT part of any supported API. If you write code that depends on
 * this, you do so at your own risk. This code and its internal interfaces are
 * subject to change or deletion without notice.</b>
 */
public class Lint {
	/** The context key for the root Lint object. */
	protected static final Context.Key<Lint> lintKey = new Context.Key<Lint>();

	/** Get the root Lint instance. */
	public static Lint instance(Context context) {
		Lint instance = context.get(lintKey);
		if (instance == null)
			instance = new Lint(context);
		return instance;
	}

	/**
	 * Returns the result of combining the values in this object with the given
	 * annotation.
	 */
	public Lint augment(Attribute.Compound attr) {
		return augmentor.augment(this, attr);
	}

	/**
	 * Returns the result of combining the values in this object with the given
	 * annotations.
	 */
	public Lint augment(List<Attribute.Compound> attrs) {
		return augmentor.augment(this, attrs);
	}

	/**
	 * Returns the result of combining the values in this object with the given
	 * annotations and flags.
	 */
	public Lint augment(List<Attribute.Compound> attrs, long flags) {
		Lint l = augmentor.augment(this, attrs);
		if ((flags & DEPRECATED) != 0) {
			if (l == this)
				l = new Lint(this);
			l.values.remove(LintCategory.DEPRECATION);
			l.suppressedValues.add(LintCategory.DEPRECATION);
		}
		return l;
	}

	private final AugmentVisitor augmentor;

	private final EnumSet<LintCategory> values;
	private final EnumSet<LintCategory> suppressedValues;

	private static Map<String, LintCategory> map = new HashMap<String, LintCategory>();

	protected Lint(Context context) {
		// initialize values according to the lint options
		Options options = Options.instance(context);
		values = EnumSet.noneOf(LintCategory.class);
		for (Map.Entry<String, LintCategory> e : map.entrySet()) {
			if (options.lint(e.getKey()))
				values.add(e.getValue());
		}

		suppressedValues = EnumSet.noneOf(LintCategory.class);

		context.put(lintKey, this);
		augmentor = new AugmentVisitor(context);
	}

	protected Lint(Lint other) {
		this.augmentor = other.augmentor;
		this.values = other.values.clone();
		this.suppressedValues = other.suppressedValues.clone();
	}

	public String toString() {
		return "Lint:[values" + values + " suppressedValues" + suppressedValues
				+ "]";
	}

	/**
	 * Categories of warnings that can be generated by the compiler.
	 */
	public enum LintCategory {
		/**
		 * Warn about use of unnecessary casts.
		 */
		CAST("cast"),

		/**
		 * Warn about use of deprecated items.
		 */
		DEPRECATION("deprecation"),

		/**
		 * Warn about items which are documented with an {@code @deprecated}
		 * JavaDoc comment, but which do not have {@code @Deprecated}
		 * annotation.
		 */
		DEP_ANN("dep-ann"),

		/**
		 * Warn about division by constant integer 0.
		 */
		DIVZERO("divzero"),

		/**
		 * Warn about empty statement after if.
		 */
		EMPTY("empty"),

		/**
		 * Warn about falling through from one case of a switch statement to the
		 * next.
		 */
		FALLTHROUGH("fallthrough"),

		/**
		 * Warn about finally clauses that do not terminate normally.
		 */
		FINALLY("finally"),

		/**
		 * Warn about issues regarding method overrides.
		 */
		OVERRIDES("overrides"),

		/**
		 * Warn about invalid path elements on the command line. Such warnings
		 * cannot be suppressed with the SuppressWarnings annotation.
		 */
		PATH("path"),

		/**
		 * Warn about Serializable classes that do not provide a serial version
		 * ID.
		 */
		SERIAL("serial"),

		/**
		 * Warn about unchecked operations on raw types.
		 */
		UNCHECKED("unchecked");

		LintCategory(String option) {
			this.option = option;
			map.put(option, this);
		}

		static LintCategory get(String option) {
			return map.get(option);
		}

		@SuppressWarnings("unused")
		private final String option;
	};

	/**
	 * Checks if a warning category is enabled. A warning category may be
	 * enabled on the command line, or by default, and can be temporarily
	 * disabled with the SuppressWarnings annotation.
	 */
	public boolean isEnabled(LintCategory lc) {
		return values.contains(lc);
	}

	/**
	 * Checks is a warning category has been specifically suppressed, by means
	 * of the SuppressWarnings annotation, or, in the case of the deprecated
	 * category, whether it has been implicitly suppressed by virtue of the
	 * current entity being itself deprecated.
	 */
	public boolean isSuppressed(LintCategory lc) {
		return suppressedValues.contains(lc);
	}

	protected static class AugmentVisitor implements Attribute.Visitor {
		private final Context context;
		private Symtab syms;
		private Lint parent;
		private Lint lint;

		AugmentVisitor(Context context) {
			// to break an ugly sequence of initialization dependencies,
			// we defer the initialization of syms until it is needed
			this.context = context;
		}

		Lint augment(Lint parent, Attribute.Compound attr) {
			initSyms();
			this.parent = parent;
			lint = null;
			attr.accept(this);
			return (lint == null ? parent : lint);
		}

		Lint augment(Lint parent, List<Attribute.Compound> attrs) {
			initSyms();
			this.parent = parent;
			lint = null;
			for (Attribute.Compound a : attrs) {
				a.accept(this);
			}
			return (lint == null ? parent : lint);
		}

		private void initSyms() {
			if (syms == null)
				syms = Symtab.instance(context);
		}

		private void suppress(LintCategory lc) {
			if (lint == null)
				lint = new Lint(parent);
			lint.suppressedValues.add(lc);
			lint.values.remove(lc);
		}

		public void visitConstant(Attribute.Constant value) {
			if (value.type.tsym == syms.stringType.tsym) {
				LintCategory lc = LintCategory.get((String) (value.value));
				if (lc != null)
					suppress(lc);
			}
		}

		public void visitClass(Attribute.Class clazz) {
		}

		// If we find a @SuppressWarnings annotation, then we continue
		// walking the tree, in order to suppress the individual warnings
		// specified in the @SuppressWarnings annotation.
		public void visitCompound(Attribute.Compound compound) {
			if (compound.type.tsym == syms.suppressWarningsType.tsym) {
				for (List<Pair<MethodSymbol, Attribute>> v = compound.values; v
						.nonEmpty(); v = v.tail) {
					Pair<MethodSymbol, Attribute> value = v.head;
					if (value.fst.name.toString().equals("value"))
						value.snd.accept(this);
				}

			}
		}

		public void visitArray(Attribute.Array array) {
			for (Attribute value : array.values)
				value.accept(this);
		}

		public void visitEnum(Attribute.Enum e) {
		}

		public void visitError(Attribute.Error e) {
		}
	};
}
